Evidence for gas nuclei in decompressed rats

In vitro and in vivo studies have shown that pressure treatment before decompression reduces bubble formation. This has been interpreted as evidence that bubbles originate from pre-existing gas nuclei. The present experiments were conducted to determine if pressure treatment during air or liquid breathing before a 2-h air dive would reduce the decompression sickness (DCS) indicence for rats. Control dives, preceded by liquid breathing with 17 and 24 rats to 135- and 150-fsw had DCS incidences of 35% and 29%. Liquid-breathing pressure treatment at 1347 fsw before 135 fsw dive (11 rats) or at 1796 fsw before the 150-fsw dive (24 rats) reduced the incidences to 0% and 8%. In the air-breathing experiments, a 240-fsw control dive with 200 rats gave an 83% incidence. Pressure treatment at 600 fsw (195 rats) or 100 fsw (153 rats) reduced the DCS incidence to 74% and 64%. These experiments suggest that the bubbles responsible for DCS in the rat originate from gas nuclei.